HONOLULU -- The Navy used one-and-a-half pounds of C-4 explosives to blast a mast off the Ehime Maru Friday.

It was the first major step in the $40 million effort to recover bodies and other items from the sunken Japanese vessel.

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The mast needed to be removed to make way for a special sling that will allow another ship to pull the ship to shallower water. Navy officials said that the process used to remove the mast is routinely utilized in offshore oil drilling.

The 190-foot Ehime Maru rests on the ocean floor nine miles south of Waikiki, where it sank after being struck by the surfacing submarine USS Greeneville on Feb. 9.

Emergency boats and a helicopter were standing by in case diesel fuel inside the fishing vessel was released from the explosion.

U.S. Pacific Fleet officials said that using the explosives was considered the safest and most controllable method to remove the mast.

The mast will be attached to lifting wires to be brought to the surface next month.

The Navy plans to move the sunken hull to 115-foot-deep waters off Honolulu International Airport in hopes of recovering the bodies of nine men and boys believed to be inside.